Green infrastructure designed to address urban drainage and water quality issues is often deployed without full knowledge of potential unintended social, ecological, and human health consequences. Though understood in their respective fields of study, these diverse impacts are seldom discussed together in a format understood by a broader audience. This paper takes a first step in addressing that gap by exploring tradeoffs associated with green infrastructure practices that manage urban stormwater including urban trees, stormwater ponds, filtration, infiltration, rain gardens, and green roofs. Each green infrastructure practice type performs best under specific conditions and when targeting specific goals, but regular inspections, maintenance, and monitoring are necessary for any green stormwater infrastructure (GSI) practice to succeed. We review how each of the above practices is intended to function and how they could malfunction in order to improve how green stormwater infrastructure is designed, constructed, monitored, and maintained. Our proposed decision-making framework, using both biophysical (biological and physical) science and social science, could lead to GSI projects that are effective, cost efficient, and just.

We assessed the prevalence and causes of sediment phosphorus (P) release within urban stormwater ponds, a process that may reduce P removal by sedimentation. Data collected from surface water of 98 urban stormwater ponds in Minnesota showed that nearly 40% had median summer total P concentrations in excess of average stormwater runoff (0.38 mg L⁻¹), implying effects of internal loading. We sampled seven ponds more intensively and found four were strongly stratified with persistent hypolimnetic anoxia, despite mean depths <2 m. Sediment core incubations revealed that, unlike in most lakes, both labile organic P (NaOH minus persulfate extractions) and redox‐sensitive P (NH₄Cl and Na₂S₂O₄ extractions) contribute to P release. Together, these analyses suggest P accumulated in stormwater ponds is highly susceptible to internal release and potentially contributes to downstream eutrophication. Understanding how frequently these conditions occur and how they affect different P forms is vital to improving pond design and management.

The methods for properly executing inspection and maintenance of stormwater control measures are often ambiguous and inconsistently applied. This paper presents specific guidelines for inspecting and maintaining stormwater practices involving media filtration, infiltration, ponds, and permeable pavements because these tend to be widely implemented and often unsatisfactorily maintained. Guidelines and examples are based on recent scientific research and practitioner experience. Of special note are new assessment and maintenance methods, such as testing enhanced filtration media that targets dissolved constituents, maintaining proper vegetation coverage in infiltration practices, assessing phosphorus release from pond sediments, and the development of compressed impermeable regions in permeable pavements and their implications for runoff. Inspection and maintenance examples provided in this paper are drawn from practical examples in Northern Midwest USA, but most of the maintenance recommendations do not depend on regional characteristics, and guidance from around the world has been reviewed and cited herein.

Virtually all land development increases stormwater runoff and disrupts the natural hydrologic cycle. This is a particularly important issue for areas developed prior to the widespread application of stormwater control measures (SCMs). Among the simplest and most underused SCMs are downspout disconnections (DSDs), whereby stormwater gutters and downspouts are disconnected from storm sewers, and stormwater is instead routed across a lawn or other pervious surfaces on the property before entering the storm drain. Seven such DSD sites within the Hewletts Creek watershed in Wilmington, North Carolina were monitored for stormwater volume, total suspended solids (TSS), and nutrient reductions over a full hydrologic year. The DSD sites had loading ratios of contributing roof area to infiltrating lawn area ranging from $4\text{:}1$ to $14\text{:}1$ . Sandy underlying soils within this watershed were expected to improve the effectiveness of these inexpensive SCMs. Significant cumulative volume reductions ($\alpha =0.05$ level) were found at each site and ranged from 42% to 87%. Significant nitrogen mass reductions (across 4 DSD sites monitored for water quality) ranged from 44% to 90% for the pollutants evaluated; however, none of the sites demonstrated significant reductions in total phosphorus (TP) or orthophosphorus (ortho-P). All TSS mass reductions were significant and ranged from 44% to 88%, with a median value of 75%. It was found that infiltration rates most significantly impacted volume reductions, whereas nutrient mass reductions correlated primarily with infiltration area length.

Watershed management has long relied on urban stormwater ponds to capture and retain phosphorus as a load reduction strategy for sensitive downst |